Method of making cutters for well drilling tools



g- 1939- A. c. CATLAND 2,168,060

' IE IHOD OF MAKING CUTTERS FOR WELL DRILLING. TOOLS Original Filed June 15, 1937 Patented Aug. 1, 1939 UNITED STATES METHOD OF MAKING CUTTERS FOR WELL DRILLING TOOLS Alfred C. Catland, Alhambra, Calif., assignor to Globe Oil Tools Company, Lon Nietos, Calii'., a. corporation of California Original application June 15, 1937, Serial No.

Divided and this application February 5, 1938, Serial No. 188,893

2 Claims.

This invention relates to a method for making cutting elements and relates more particularly to a method for making cutters for well drilling tools. A general object of this invention is to provide a simple, commercially practical method for making effective well tool cutters.

This application is a division of my application for Letters Patent of the United States, Serial No. 148,298, filed June 15, 1937, entitled Cutter for well drilling tool.

The cutters of rotary well drilling tools are subjected to severe wear and it has been the general practice where possible to face the active parts of the cutters with hard, abrasion resisting materials. The cutting parts of well tools operating by scraping or abrasive action usually have quite large surfaces makin it possible to face them with welded on or brazed on abrasion resisting materials. However, cutting elements that operate by a percussive action such as the roller cutters of a rock bit usually have small cutting parts or teeth and it is very difficult to weld, braze or cast hard cutting material on their faces without making their cutting edges blunt and ineffective.

An object of this inventionis to provide an effective method for incorporating abrasion resisting material in the teeth of a roller cutter of the type that operates by a percussive action.

Another object of this invention is to provide a practical method for providing abrasion resisting elements on the teeth of a roller cutter without thickening the teeth and without rendering the active edges of the teeth blunt.

Another object of this invention is to provide a method for incorporating extensive bodies of hard wear resisting material in the central zones of the teeth of a preformed cutter.

Another object of this invention is to provide a method of the character mentioned in which the hard abrasion resisting elements are accurately located and dependably bonded with the material of the teeth.

A further object of this invention is to provide a method of the character mentioned for making a roller cutter whose teeth are self-sharpening through use.

The various objects and features of my invention will be fully understood from the following detailed description of typical preferred manners of carrying out the method of my invention, throughout which description reference is made to the accompanying drawing, in which:

Fig. 1 is an end elevation of a pre-formed cutter illustrating the slots in the cutter teeth for the reception of the hard cutting elements. Fig. 2 is a fragmentary end elevation of the cutter illustrating the ends of the teeth following the brazing and welding operations. Fig. 3 is a fragmentary longitudinal sectional view of the finished cutter. Fig. 4 is an enlarged transverse detailed sectional view of one of the teeth of the cutter before the insertion of the wear resisting element. Fig. 5 is a view similar to Fig. 4 shoW-. ing one form of insert or abrasion resisting element in position in the slot. Fig. 6 is a view similar to Fig. 5 illustrating the abrasion resisting element brazed to the tooth and Fig. '7 is a fragmentary view similar to Fig. 5 illustrating another form of abrasion. resisting element in position in the slot following the brazing operation. i

The method of the present invention may be employed in connection with the manufacture of well tool cutting elements and similar devices of different characters, shapes, etc The invention is particularly adapted for use in conjunction with the manufacture of percussive cutting elements and in the following detailed description I will describe the method as employed in the manufacture of a roller cutter for a well drilling bit or the like. It is to be understood that the invention is not to be construed as limited or restricted to the specific application of the invention about to be described. 1

The roller cutter illustrated in the drawing is intended to be rotatably supported on a well drilling tool so that its cutting parts or teeth have rolling engagement with the earth formation and, therefore, a percussive cutting action on the formation. The cutter includes a body l0 provided at its periphery with a. multiplicity of cutting teeth H. The body II] has a central longitudinal opening 13 to facilitate its rotatable mounting on a.tool. The opposite ends i l of the cutter body l0 are flat and parallel and the cutter is frusto-conical, that is, the periphery of the body ill slopes or inclines relative to the longitudinal axis of the body. The cutting teeth H are arranged longitudinally on the periphery of the cutter l0 and are equally transversely spaced. The ends of the teeth II at the large end of the body l0 are bevelled off and the adjacent portions of the body may be bevelled in a similar manner. In accordance with the invention, the teeth II are substantially V-shaped in transverse cross section having outwardly convergent sides IS. The roller cutter just described may be cast or formed in any otherpractical manner.

The improved method of the present invention comprises, generally, the provision of slots 23 in the cutter teeth II, the arrangement of elements l2 or l2a-of abrasion resisting material in the slots 23 and the brazing of the elements I 2 or l2a to the teeth Ii.

The slots 23 may be formed'in the teeth H in any suitable manner; For example, they may be cut or milled in the teeth following the cast ing or forming of the cutter. The slots 23 extend longitudinally of the teeth II and there is preferably a single slot in each tooth. The slots 23 extend between the opposite ends of their respective teeth II and occupy the medial longitudinal planes of the teeth. As illustrated.

be of the same size and shape and may have substantially parallel side walls.

The abrasion resisting elements l2 or l2a are intended to be incorporated in the teeth II to make the teeth particularly effective, long wearing, and self-sharpening through use. The elements l2 or l2a are shaped and proportioned to occupy the slots 23 so that their outer edges I! or i8a occur at the crests of the teeth. The invention contemplates the employment of either form of abrasion resisting element l2 or I211.

The hard abrasion resisting elements I2 are in the form of sheets or plates of pre-sintered or pre-cast abrasion resisting material such as tungsten carbide, or the like. Prior to the insertion of the elements l2 in the slots 23 each element is wrapped with a foil 20 of copper, aluminum or similar material for brazing the elements to the walls of the slots. The elements l2a are proportioned so that they rather accurately fit the slots 23 when provided with the foil 20. The foil 20 is adapted to cooperate with the bottom walls as well as the side walls of the slots 23.

The hard abrasion resisting elements l2a are formed of granular or powdered tungsten carbide or other hard abrasion resisting material mixed with powdered copper or other metal having a lower melting point than steel. The granular or powdered abrasion resisting material and the powdered copper are pressed into the selfsustaining sheets or plates which constitute the elements i2a. The unsintered elements l2a are shaped and proportioned to fit the slots 23 so that their surfaces cooperate with the bottom and side walls of the slots and so that their outer edges i8a occur at or are exposed at the crests of the teeth ll.

Following the insertion of an abrasion resisting element l2 or l2a in a slot 23 of a tooth H the said tooth is heated in a'suitable atmosphere and brought to the melting point of the aluminum or copper foil 20 of the element i2 or to the melting point of the powdered copper of the element i2a. When the tooth slot 23 contains an element l2 the heating of the tooth melts the foil 20 so that the foil dependably bonds or brazes the element i2 to the metal of the tooth II or to the walls of the slot 23. Fig. 6 of the drawing illustrates an abrasion resisting insert or element i2 finally brazed in the slot 23 of a tooth II. If an element I2a is inserted in a slot 23 the heating of the tooth I I, as described above, melts the powdered copper of the unsintered element i2a so that the element is simultaneously sintered into a substantially homogeneous mass and bonded or brazed to the metal of the tooth ll defining the walls of the slot 23.

The heating of a tooth'li as just described thus completes the bonding or brazing of the element I 2 or i2a as the case may be, in the slot 23 to constitute a rigid part of the tooth. It will be readily understood how the abrasion resisting elements l2 or l2a may be brazed in the slots 23 of the several teeth II to provide the teeth with hard cutting inserts. Following the brazing or bonding of the elements l2 or l2a in the teeth I I the outer edges it or l3a of the elements may be sharpened to constitute the cutting edges of the teeth.

Following the brazing of the inserts or elements i2 or In in the slots 23 the bevelled ends of the teeth Ii at the large end of the frusto-conical cutter body l0 may be faced with tungsten carbide or other abrasion resisting material II. The material I I may be welded to the teeth H and. to adjacent parts of the cutter body Ill and may be bevelled off in conformity to the bevelled en of the teeth ll. I

It is believed that the method of the present invention will be readily understood from the foregoing detailed description. The hard abrasion resisting inserts or elements l2 or l2a. are easily and quickly bonded or brazed to the teeth ll. longitudinal planes of the teeth ll so that they are supported and backed up by the materialjof the teeth and are not subject to fracture or failure. The method of the invention is rapid and may be carried out with simple, typical equipment. The incorporation of the elements I! or l2a in the teeth ll makes the teeth long wearing and self-sharpening through use. After the cutter has been in service for some time the teeth ll may gradually wear away. The teeth ll wear away at their sides I! and as they wear the outer active edges I3 or |8a of the elements l2 or l2a are exposed. This continuous or progressive exposure of the hard abrasion resisting plates or elements i2 or l2a at the crests of the teeth ll throughout the life of the teeth makes the teeth self-sharpening. The elements l2 or In being exposed to the crests of the teeth ll insure the even wearing of the teeth so that the teeth may retain their original general configuration when worn. The elements l2 or i2a are of substantial depth or width giving the teeth II a long life. The hard abrasion resisting elements l2or l2a may be of like size and shape so that the several teeth ll of the cutter wear evenly or uniformly to assure a uniform cutting action throughout the circumference of the cutter.

Having described only typical preferred manners of carrying out the method of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to. myself any variations or modifications that may appear to those skilled in the art or fall within the. scope of thefollowing claims.

Having describedmy invention, Iii-claim:

1. The method of incorporating abrasion resisting material in the body of a tooth comprising providing a slot in the tooth, providing a pressed sheet of powdered abrasion resisting material and copper, placing said sheet in the slot, and then heating the tooth to sinter the sheet and fuse it to the walls of the slot.

2. The methodof making a roller cutter comprising forming a cutter body having cutting teeth, providing substantially medial longitudinal slots in the teeth, providing unsintered'plate-like elements of granular abrasion resisting material andbrazing material, arranging said elements in the slots to have edges at the crests of the teeth, and then heating the teeth to sinter said elements and braze them to the teeth.

ALFRED C. CATLAND.

The elements l2 or l2a occupy the central 

